Triacetone triperoxide (TATP) is an explosive that is very easily prepared and whose starting materials are readily available from drugstore articles (J. Zabicky, The chemistry of peroxides, John Wiley & Sons, Ltd; (2006); J. P. Agrawal, R. D. Hodgson, Organic Chemistry of Explosives, John Wiley & Sons, Ltd; (2007)). In addition, the starting materials (hydrogen peroxide, acetone and acid) are easily accessible in large amounts. Since this explosive is very sensitive to heat, impact and electrostatic discharge and requires no initial ignition and in addition has an explosive force comparable to that of TNT, it has no commercial or military relevance. However, due to its easy accessibility, it is often employed for terroristic purposes (e.g., Madrid, March 2004, London, July 2005). For this reason, a simple and quick online detection is necessary to avert dangers. Currently, the following detection methods are known (J. W. Gardner, J. Yinon (Eds.), Electronic Noses & Sensors for the Detection of Explosives, Kluwer Academic Publishers (2003); U.S. Pat. No. 7,159,463; Z. Lin et al., Anal. Chem. 65, 1546-1551 (1993); E. Uttenthaler et al., Biosensors & Bioelectronics 16, 735-743 (2001); DE-A-10109534):
Separation by RP-HPLC: Separation of a sample solution by RP-HPLC, decomposition of the TATP to hydrogen peroxide using a UV lamp, and determination of the hydrogen peroxide concentration by means of fluorescence spectroscopy. With this method, online measurement is not possible, since a sample solution needs to be prepared first, which can be examined further only with a great analytical effort.
Photometry: Treatment of a sample solution with peroxidase to destroy any traces of hydrogen peroxide, followed by irradiating this solution with a UV lamp to decompose TATP to hydrogen peroxide, and after the addition of a reagent solution, the sample is finally examined by photometry using a UV/Vis spectrometer. This method is portable, but the preparation of a sample solution is necessary. In addition, it requires a high analytical and apparative expenditure and is not suitable for online examinations.
E-3500: In this method, the sample is collected by manual swabbing (perhaps first danger of explosion)! After being applied to a metal disk, the analyte is thermally decomposed. With luminol, the oxidative decomposition products formed produce a chemoluminescence, which can be measured. Due to the necessary manual effort, online measurement is not possible, and application to personnel security screening is doubtful. This system does not have sufficient chemical selectivity, since there is no separation of the analytes. Thus, any substance that releases oxidizing decomposition products upon heating will be considered to be TATP.
Z nose: The z nose is a miniature variant of a gas chromatography with a down-stream SAW (surface acoustic wave) sensor as a mass-sensitive detector. The recognition of the substances is effected by comparing the retention times with an alkane standard. In this method too, the sample is preliminarily enriched before the actual analysis, so that online measurement is no longer possible.
Mini-nose: The mini-nose is a system constituted of two modules. The first of these modules is used to collect and enrich the sample. The second module analyzes the collected sample. In the second module, a sensor array consisting of several coated HFF oscillating quartz crystals is contained. For the measurement, the initially collected analyte is desorbed from module one into module two. After another 60 s of measuring time, the substance is then identified by means of main component analysis. In this case too, it is obvious that online examination is not possible due to the necessary enriching step.
WO02/103340 describes the use of an oscillating quartz crystal array with high frequency quartz crystals, so-called HFF quartz crystals. However, the sensor array used in each method is so insensitive that an enriching step is necessary before the actual detection.
However, every one of these methods involves drawbacks rendering it unfit for online monitoring: Either it requires a high analytical apparative expenditure, or it has a high detection limit (enriching may be necessary), or the measuring interval is too long, the method is non-selective before a chemically similar background, or it is required for TATP to be in a liquid phase. This means that detection of TATP traces in the air has been possible only after enriching or with a high analytical expenditure. This precludes the online monitoring of people and/or objects for averting dangers. Thus, a simple and quick detection of the explosive TATP would be very welcome.